I have written a book on the politics of autism policy. Building on this research, this blog offers insights, analysis, and facts about recent events. If you have advice, tips, or comments, please get in touch with me at jpitney@cmc.edu

Researchers studied the records of 95,727 children with older siblings who were enrolled in health plans from 2001 to 2012. Of those, 1,929 children had an older sibling who’d been diagnosed with autism spectrum disorder (ASD).

The MMRvaccination rate for children without siblings with autism was 92 percent by the age of 5. The rate was 86 percent for children who had an autistic sibling. This may reflect the mistaken belief held by some parents that the MMR vaccine increases autism risk in vulnerable kids. In all, 994 children in the study were diagnosed at some point with ASD. Of those, 134 had a sibling with the disorder. The other 860 did not.

Researchers said there was no difference in ASD diagnoses among the children with autistic siblings in the vaccinated and unvaccinated groups. The same was true for children with no autism cases in their immediate family.